Load bearing air cushion apparatus

ABSTRACT

Apparatus capable of lifting, supporting, and moving weight on cushions of air wherein air is controllably admitted under pressure into areas encompassed by bounding sealing assemblies to form supporting cushions between the base of said apparatus and a support surface over which the apparatus moves, or alternatively between the base of said apparatus and a flat-bottomed load moved across its air cushions, with faces of said sealing assemblies spaced a small distance from said support surface or flatbottomed load by air leakage under the sealing means, each said sealing assembly comprising a flexible airtight hanger and annular structure projecting downward from the hanger. The annular structure includes resilient mounting means attaching the sealing means to the hanger.

ilnited States Patent 1191 Vaughen 1 July 9,1974

Creek Rd., Palos Verdes Peninsula, Calif. 90274 [22] Filed: Dec. 16, 1971 [21] Appl. No.: 208,879

Related U.S Application Data [63] Continuation-in-part of Ser. No. 819,860, April 28, 1969, abandoned, which is a continuation-in-part of Ser. No. 734,361, June 4, 1968, abandoned.

3,347,329 10/1967 Jones 180/128 3,385,390 5/1968 Guienne... 180/116 3,400,779 9/1968 Grace 180/128 X 3,401,767 9/1968 Barr 180/127 X 3,414,075 12/1968 Bertin 180/121 3,500,948 3/1970 Williamson et a1. 180/124 3,513,934 5/1970 Crowley 180/124 Primary ExaminerDavid Schonberg Assistant ExaminerLeslie J. Papemer Attorney, Agent, or FirmSmyth, Roston & Pavitt [5 7] ABSTRACT Apparatus capable of lifting, supporting, and moving weight on cushions of air wherein air is controllably admitted under pressure into areas encompassed by bounding sealing assemblies to form supporting cushions between the base of said apparatus and a support surface over which the apparatus moves, or alternatively between the base of said apparatus and a flatbottomed load moved across its air cushions, with faces of said sealing assemblies spaced a small distance from said support surface or flat-bottomed load by air leakage under the sealing means, each said sealing assembly comprising a flexible airtight hanger and annular structure projecting downward from the hanger. The annular structure includes resilient mounting means attaching the sealing means to the hanger.

18 Claims, 12 Drawing Figures PAIENIEUJm sum SHEEI 1 (If 9 PATENIEDM 9mm smear 9 Y I PATENIEM. 91974. 3.822.761-

SHEUBUFQ I LOAD BEG AIR CUSIHON APPTUS CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser.. No. 819,860, filed Apr. 28, 1969 and now abandoned, which, in turn, is a continuation-in-part of my earlier application Ser. No. 734,361 filed June 4, 1968 and now abandoned.

This invention describes apparatus capable of supporting and moving weight on cushions of air and relates in part to air cushion supported cargo platfonns and containers generally of the type disclosed and claimed in my previously issued US. Pat. No. 3,055,446. That patent specifies the use of vertically slidable brushes as air barriers to surround the lifting air cushions. These brushes are mounted as close fitting collars surrounding boxlike cavities underneath the platform or container.

Tests have demonstrated that the use of vertically retractable brushes as sealing means to surround the individual air cushions produces an air cushion vehicle which is capable of operating over weathered asphalt and concrete surfaces normally encountered in outdoor cargo handling areas.

A primary object of the present invention is to retain this capability of the sealing means to operate over normally encountered outdoor surfaces while increasing the air pressure which can be built up inside the air cushions. This increased operating pressure inside the lifting air cushions greatly increases the weight which can be supported by a cushion of a given platform area. Additional objects of the present invention include:

1. Disclosure of a family of complete air cushion load bearing and transporting systems which are compatible with currently used methods of cargo handling;

2. Reduction of lifting horsepower required to support a given weight compared to the original brush seals shown in US Pat. No. 3,055,446;

3. Description of a family of different sealing means to surround lifting air cushions which are capable of holding air pressure in the cushions while operating over a wide range of surfaces from smooth metal decking to weathered asphalt;

4. Provision of flexible sealing means that automatically accommodate to rolling variations of the operating surface;

5. Incorporation of a self-jacking capability which may be separately controlled;

6. Inherent damping of dynamic bounce often encountered by highly loaded air cushion support devices;

7. Accommodation of a wide range of off-center loads and separate control of the tilt angle of the air cushion supported device;

8. Accommodation of a relatively large volume flow of air at relatively low pressure so that air losses when passing over an obstacle represent a small proportion of the total air being supplied;

9. Distribution of the load over the largest possible base area to minimize footprint pressure of the air cushions on the supporting surface;

10. Provision of sealing means with high wear resistance and reliability which do not have vulnerable thin wall, flexible, inflatable diaphragm elements in direct contact with the operating surface over 2 which the air cushion supported device is moved.

Other objects, advantages and features of my invention will become evident from examination of the accompanying drawings of which:

FIG. 1 is an overall perspective view of an air cushion supported cargo handling system comprising interconnected air cushion modules for end insertion under auxiliary cargo conveyances;

FIG. 2 is a perspective view of the foldable air inlet manifold in FIG. 1 which attaches with quickdisconnect fittings to an air cushion pallet;

FIG. 3 is a bottom plan view of an air cushion pallet and its air inlet manifold shown in FIG. 1;

FIG. 4 is a perspective view, partially in section showing a structure for preventing air leakage at the tangent points of two sealing assemblies in FIG. 3;

FIG. 5 is a cross-sectional view of a low profile sealing assembly in FIG. 3;

FIG. 6 is an exploded perspective view showing the structure of one of the air cushion pallets of FIG. 1;

FIG. 7 is a perspective view, partially cut away to show the construction of an inflatable in FIG. 5 hanger;

FIG. 8 is a bottom plan view of an air cushion platform;

FIG. 9 is a cross-sectional view showing a single high profile sealing assembly;

FIG. 10 is a bottom plan view of an air cushion vehicle;

FIG. 11 is a perspective view of a portion of the bottom of the air cushion vehicle shown in FIG. 10; and

FIG. 12 is a cross-sectional profile view showing one of the pressure actuated doors located inside the air inlet of the air cushion vehicle;

In FIG. 1 a cargo handling system consists of the following components:

I. A cargo bearing auxiliary conveyance 169 with integral supporting skids 170,

2. Interconnected air cushion modules 172, 173, 174,

3. A source of relatively high pressure air comprising a bleed air gas turbine 175,

4. An air source transport means comprising a wheeled dolly 176, and

5. Translational motive means comprising a tow tractor 177.

Floatation air for the interconnected air cushion pallets 172, 173, 174, is provided by an air source comprising for example a bleed air gas turbine which combines air compressor, drive mechanism, and prime mover into one integral unit. This unit is transported on a wheeled dolly 1'76. Relatively high pressure bleed air from the turbine is passed through air duct 179. Heated exhaust gas from the turbine may either pass directly to the atmosphere through the tail pipe or it may be diverted by a valve 181 to pass through a heat exchanger 182 which surrounds the air duct 179. This preheats the floatation air prior to entering the interconnected air cushion pallets. Before this relatively high pressure bleed air is introduced into the inlet manifold of the air cushion pallets it may also be expanded to a large volume of lower pressure air to float the pa]- lets. This is accomplished in the round cross section, flexible air duct 183. This duct 183 tapers from a relatively small diameter where it attaches to the outlet of heat exchanger 182 to a much larger diameter where it attaches to a flared transition collar 185 on the top surface of the air inlet manifold 184 of the interconnected air cushion pallets.

When the auxiliary cargo conveyance 169, is floated by the air cushion pallets 172, 173, 174, the whole assembly can be moved across the floor virtually without friction. The required translational motive force can be provided by a powered tractor tug 177. Towing force is applied to the air cushion pallets through towing hitch 186 which is integral with air inlet manifold 184.

FIG. 2 is an enlarged perspective view of an air inlet manifold 184. The forward vertical face 195 of this inlet manifold butts against the end of any one of the air cushion pallets 172, 173, 174 and is held in position by quick disconnect fittings 187, 188. After the air inlet manifold is removed from the air cushion pallet, its width may be reduced for ease in transport by folding the outer portions. In FIG. 2, outer portion 189 is shown in the down position ready to attach to the air cushion pallet while outer portion 190 is shown folded along a hingeline which approximately coincides with the top horizontal surface of air inlet manifold 184.

FIG. 3 is a bottom plan view of one air cushion pallet 172 with its air inlet manifold 184 attached by fittings 187, 188. The bottom skin of manifold 184 and pallet 172 is partially cut away at 191 to show details of mating the inlet manifold with the air cushion pallet. Internal structural beams 192, 193 run the full length of the air cushion pallet producing an air duct down the middle of the pallet. As shown in FIG. 2, an opening 194 is provided in the vertical face 195 of air inlet manifold 184. As shown in FIG. 3, this opening 194 aligns with a check valve 196 which is mounted in the vertical end face of air cushion pallet 172. Air can therefore pass freely from the interior of air inlet manifold 184 into the space inside the air cushion pallet between beams 192 and 193. However, the check valve 196 prevents air from flowing in the opposite direction. An additional opening 197 is provided in the vertical end face of the air cushion pallet. When air inlet manifold 184 is attached to air cushion pallet 172, this opening 197 is covered by the vertical face 195 of the air inlet manifold which does not have a matching opening. However, when air inlet manifold 184 is removed from air cushion pallet 172, opening 197 is exposed thus allowing air to escape from the space inside the air cushion pallet between beams 192 and 193.

As shown in FIG. 3, four separate circular sealing assemblies contain four separate air cushions under the pallet 172. The airflow required to maintain these air cushions is directly related to the external periphery of the sealing means across which a pressure drop must be developed. This exposed external periphery can be minimized by making the circular sealing means tangent to each other and providing airtight contact at these points of tangency.

FIG. 4 illustrates a method of providing an airtight seal between flexible elements 199 in their area of tangency. FIG. 4 is a perspective view, partially in cross section, taken through section 4-4 of FIG. 3 with the air cushion pallet 172 inverted.

In FIG. 4 the tangent vertical walls of flexible elements 199 of the sealing assemblies are sealed together by bonding to two strips of airtight fabric 203, 204 which are stitched and bonded together at their midsection 205.

FIG. 5 is a cross-sectional view taken along the line 55 of FIG. 3 showing a low profile sealing assembly. The flexible seal hanger 200 is attached to the bottom surface 206 of the air cushion pallet by structural mounting rings 207 and 207-A. These structural mounting rings have upper horizontal faces which bear against the bottom surface of the air cushion pallet and have lower horizontal flanges 208 and 208-A respectively each of which is parallel to the bottom surface of the air cushion pallet but spaced a small distance vertically below it. This horizontal flange serves as a base for the air cushion pallet to rest on without crushing the deflated sealing assemblies when no air is supplied. It also serves as a protective cover for the inflatable seal hanger 200 to prevent it from being damaged by objects which may be encountered on the operating surface. Air to inflate hanger 200 may be admitted through one or more openings 33 in the bottom plate 206 of the pallet.

FIG. 1 shows three interconnected pallets 172, 173 and 174. Pallets 172 and 173 are identical to each other but pallet 174 has chamfered rear corners and a sloped upper surface to facilitate insertion under auxiliary cargo conveyances 169 and 171. Air inlet manifold 184 may be interchangeably mounted on the three pallets 172, 173, and 174, since all pallets are fitted with receptacles for quick disconnect fittings 187 and 188.

An air seal must be provided by suitable sealing means to prevent floatation air from leaking out of the juncture between adjacent air cushion pallets. In FIG. 3 this seal is provided by flexible sponge rubber gaskets 211, which are mounted on matching end faces of the air cushion pallets and which yield to permit relative angular movement of the pallets. Quick disconnect latches 213 are mounted on the sides of the air cushion pallets to connect adjacent pallets together.

As shown in FIGS. 3 and 5 the structure of each air cushion pallet consists of a lower skin 206 and an upper skin 215 separated by external solid web beams 216, internal solid web beams 192, 193, 229, 230 and internal structural spacers 217. The construction of the internal structural spacers is shown in the exploded perspective view of FIG. 6. The internal structural spacer 217 consists of two flat sheets 218, 219 into which have been formed an arbitrary number of raised truncated conical stand-offs 220. The abutting faces of these standoffs are structurally attached together by welding, bonding, or other attachment means. Skins 206, 215 are then attached to the external surfaces of the assembled internal spacers 217 to complete the assembly.

As shown in FIG. 3, internal solid web beams 192, 193, 229, 230 divide the interior of the air cushion pallet into five separate air passages which run the full length of the pallet. The spaces between the internal beams are filled with the structural spacer assemblies 217. As shown in FIG. 6, however, when the standoffs 220 are attached together to assemble each structural spacer 217 air may pass freely through the interior of the structural spacer by flowing around the standoffs 220. Therefore air which is introduced into one end of the air cushion module can flow freely down the length of the module.

As previously described air is introduced into the space between internal beams 192 and 193 through check valve 196. This duct carries air to an arbitrary number of openings 33 (FIG. 5) in the lower skin 206 of the air cushion pallet to inflate flexible seal hangers 200.

As shown in FIG. 3, the air passageway between internal beam 230 and external beam 216 on the left of FIG. 3 which forms one edge of the air cushion pallet, carries floatation air to opening 235 in the bottom surface of the pallet to supply floatation air to air cushion 236. The air passageway between internal beams 193 and 230 carries floatation air to opening 237 in the bottom surface of the pallet to supply floatation air to air cushion 238. The air passageway between internal beams 192 and 229 carries floatation air to opening 239 in the bottom surface of the pallet to supply floatation air to air cushion 240. The air passageway between internal beam 229 and external beam 216 on the right of FIG. 3 which forms one edge of the air cushion pallet, carries floatation air to opening 241 in the bottom surface of the pallet to supply floatation air to air cushion 242. Therefore the structural framework of the air cushion pallet effectively provides separate air ducts to supply floatation air to the separate air cushions.

In FIG. 5 a sealing means 221 on the underside of hanger 200 is a smooth faced low profile seal without bristles. The sealing means 221 is relatively stiff across its width but flexible along its periphery.

A mounting means 224 for the sealing means 221 is installed between the sealing means 221 and the inflatable seal hanger 200.

The mounting means 224 is a simple airtight sponge rubber block which is bonded along its upper surface to the flexible seal hanger 200 and along its lower surface to the abrasion resistant sealing means 221.

When relatively high pressure air is introduced into the air ducts of the pallet, it inflates thecorresponding flexible seal hangers 220 thereby pressing the sealing means 221 downward against the ground. This produces a positive air sea] around each air cushion and allows the air pressure in the air cushions to build up to the level required to life the pallet off its structural supports 207. A small gap will then develop between the lower face of each sealing means and the ground allowing floatation air to escape underneath the sealing means. The pallet can then be moved across the ground virtually without friction.

Since the four circular sealing means 221 in FIG. 3 are interconnected in a fluid-tight manner at their tangent points, they form a central cavity 222-A in which an air cushion is formed by leakage from the internal segments of the four cushions. The leakage is under the four circular sealing means 221 adjacent the'ground surface that is transversed by the pallet. When the air pressure inside the central cavity 222-A matches the pressure inside the four circular sealing means 221 there is no pressure differentiation across the internal segments of the sealing means and consequently the total amount of air that is lost by leakage is greatly reduced.

The flexible mounting means 224 shown in FIG. 5 is mounted to the underside of the air cushion pallet by a flexible, inflatable seal hanger 200 which is shown in the inflated configuration in FIG. 5. As shown in FIG. 7 this sea] hanger may be constructed of at least one layer of airtight fabric 225 which is elastic in all directions as indicated by arrows 226. This elastic fabric is reinforced by an arbitrary number of strips of relatively inelastic fabric 227 to control the extension of the seal hanger due to air pressure in the space above the hanger 113.

As previously described, the structural beams which form the framework for each air cushion module also form separate air passageways to supply air to the separate air cushions. The flow of air into these four passageways is controlled by four doors 231, 232, 233, 234 mounted in the air inlet duct as shown in FIG. 2. The positions of these doors may be separately controlled by any mechanical means such as the electric motor driven actuators 243. By controlling the air flow to the separate air cushions it is possible to accommodate a wide variation in the load center of gravity. If a load with oflset center of gravity is to be carried the doors are separately adjusted to provide a greater flow of air into the cushions which are most heavily loaded and a lesser flow into the lightly loaded cushions.

FIG. 9 is a cross-sectional view taken along the line 9 9 of FIG. 8 showing a sealing assembly of an air cushion platform. A flexible seal hanger 336, 337 is attached to the bottom surface 320 of the air cushion platform by structural mounting rings 338, 339. The two halves of this flexible seal hanger are attached along their lower edges by airtight means to a floating structural ring 340. The seal hangers 336, 337 may be constructed of flexible airtight material which is capable of omnidirectional stretch as indicated by arrows 226 in FIG. 7.

The airtight seal hanger is inflated through a separate air supply line 342. This air line is fitted with an adjustable two-way valve 343 which can admit air to the seal hanger through a controllable orifice. Incoming air flow is indicated by arrow 344. This valve can also be turned to allow air trapped inside the seal hanger to escape to the atmosphere when the air cushion platform is at rest as indicated by arrow 345. With this arrangement, the inflation pressure of the seal hanger is independent of the pressure in both the air cushion and the plenum chamber of the air cushion platform.

Since the flexible seal hanger is stretchable and its internal air pressure can be set at any desired value, it may be appropriate to fit the seal hanger with physical stops to limit its downward extension.

Even though the average downward extension of the saling means should be controlled, it is also desirable to allow the sealing means to tilt relative to the air cushion platform so it can follow rolling variations of the terrain over which the air cushion platform is operated. A stop mechanism which fulfills this dual requirement is shown in FIG. 9. In FIG. 9, each stop mechanism consists of two fixed length, flexible links 350, 351 attached to diametrically opposite points of floating structural ring 340. The upper ends of links 350, 351 are attached to the horizontal arms of bell cranks 352, 353 which are pivotally mounted on trunnions inside the structure of the air cushion platform. The vertical arms of bell cranks 352, 353 are then connected together by a fixed length structural link 354 which is pivotally attached at its opposite ends to the bell cranks.

In FIG. 9 the sealing means consists of an arbitrary number of concentric layers of airtight, abrasion resistant, flexible skirt material 361. These layers are permanently clamped into flat structural header 362.

The sealing means shown in FIG. 9 is attached to structural ring 340 by a flexible mounting means. This flexible mounting means consists of a flexible curtain 363 which may be an extension of the flexible seal hanger. The flexible curtain 363 may be fitted with an airtight zipper 365 which extends around the entire periphery of the air seal and facilitates removal of the sealing means 361 from the structural ring 340.

In the inflatable seal hangers shown in FIG. 9 an effective spring rate with respect to vertical resilience is provided by the omnidirectional elasticity of the seal hanger material as indicated by the arrows 226 in FIG. 7. Damping of the inflatable seal hanger is provided by adjustment of valve 343 to control an orifice in line 342 which supplies air to the seal hanger.

In FIG. 9 a block of material 367 having high elasticity and inherent damping is mounted between structural ring 340 and seal header 362. Examples of suitable materials for this application are open cell sponge rubber and synthetic foam materials.

Since the sealing assemblies are suspended below the bottom surface 320 of the air cushion platform, means must be provided to prevent the dead weight of the platform from crushing the sealing assemblies when there is no air being supplied to the air cushions. As shown in FIG. 8, structural beams 368, 369, and 370 are attached to the underside of the air cushion platform inside of the air cushions. The depth of these beams is at least as great as the collapsed height of the sealing assemblies. To disburse the air flowing into the air cushions during operation of the air cushion platform, a circular plate 371 is attached to the lower flanges of beams 368, 369, 370. This circular plate has a diameter only slightly less than the inside diameter of the sealing assembly. Therefore air enters the lifting air cushion through an annular opening which has much greater area than the feed holes 332 or 334 in the bottom surface 320 of the air cushion platform. The result is that lifting air will enter the space between plate 371 and the load bearing surface at a relatively low velocity thereby minimizing disturbance of dust which may be laying on the load bearing surface.

When an air cushion cargo conveyance is at rest on the surface over which it operates, floatation air must be admitted to the lifting air cushions. When this floatation air inside the cushions builds up sufficient pressure to balance the weight of the air cushion conveyance, the bottom ofthe conveyance will lift off of the operating surface and the conveyance will be supported entirely on the air cushions. To enable the air pressure to build up inside the lifting cushions, it is necessary to provide an effective sealing means surrounding each cushion. This is best accomplished by pressing each sealing means firmly against the operating surface while air pressure inside the cushion is building up. Since in this invention each sealing means is mounted on an inflatable, flexible hanger the sealing means will be pressed against the operating surface if the seal hanger is inflated to its full operating pressure before floatation air is admitted into the lifting air cushion. This requirement can be satisfied automatically if a pressure-sensitive door is placed across the inlet of each air duct inside the air cushion vehicle. These doors should remain closed until the air pressure inside the air inlet and the duct which inflates the seal hangers reaches a predetermined value. At that point, the doors should open automatically to admit floatation air into the ducts which supply the air cushions. FIG. 12 is a cross-sectional profile view of one of the pressure actuated doors located across the an air duct.

Each pressure actuated door 560 is a threedimensional object of uniform cross section which extends entirely across the inlet of one air duct. The door has two mutually perpendicular flat sides 561, 562, and is hinged to the air cushion base by hinge 563 which is mounted along the intersection of these two mutually perpendicular sides. When door 560 is in the closed position as shown by the solid outline in FIG. 12, side 561 is essentially vertical and side 562 is horizontal. A third side of the three dimensional door is a cylindrical surface 564 which has a constant radius to the centerline of binge 563. Flat side 561 has a small protrusion or lip 565 which extends beyond the intersection with curved side 564 and flat side 562 has a similar protrusion 566. Each door 560 is mounted in a separate opening provided in the upper plate 541 of the air cushion base 529. Protrusion 566 interferes with the edge of this opening to prevent door 560 from rotating clockwise any farther than the position shown by the solid outline in FIG. 12. Protrusion 566 interferes with the edge of this opening to prevent door 560 from rotating counterclockwise any farther than the position shown by the dotted outline in FIG. 12. Each door 560 is provided with a spring 567 which tends to hold the door in the closed position indicated by the solid outline in FIG. 12.

The operation of this pressure sensitive door is as follows. When air is introduced into inlet 536 as indicated by arrow 568, door 560 is in the closed position indicated by the solid outline in FIG. 28. Air pressure will build up in inlet 536 and the air duct which has no door and inflates the seal hangers. This air pressure will create forces against the vertical face 561 of door 560 as shown by the small arrows 569. These pressure forces which act normal to surface 561 create a counterclockwise moment about hinge 563 tending to open the door. They are resisted by spring 567, but when air pressure in the inlet 536 reaches a certain predetermined value the air pressure forces will overcome the spring and the door will open. Once the door begins to open, air can flow down the duct toard the air cushion as indicated by arrow 570. As air pressure builds up downstream of the door, pressure forces will build up on the curved surface 564 as indicated by the small arrows 571. Pressure forces always act normal to the surface on which they bear. Since the curved surface 564 has its center of curvature coincident with the axis of hinge 563, all pressure forces 571 effectively act through the hinge line. Therefore, with this configuration for door 560, the downstream pressure forces 571 are incapable of producing a moment about the hingeline of the door. The door is affected only by the pressure forces 569 which act normal to flat surface 561, and by the pull exerted by spring 567.

FIG. 10 is a bottom plan view of base 529 of an air cushion vehicle. This base is fitted with a number of separate adjacent air cushions 572, 573, 574, etc. Each air cushion is surrounded by a sealing means 575, 576, 577, etc. which is circular in plan view around its external periphery. To minimize peripheral leakage, however, these sealing means are mounted immediately adjacent to each other.

FIG. 11 is a perspective view of a portion of the sealing assembly. As shown in this figure each sealing means 575, 576, 577 etc. is circular along its external inlet of periphery but is straight along each side which is adjacent to the next sealing means. Since these straight sides 578, 579 etc. press tightly together when the air cushions are inflated, net leakage from the air cushions can occur only under the cylindrical, external, curved portions of the sealing means. This geometry of the sealing means insures that a maximum lifting cushion area is enclosed within a minimum of external leakage periphery. If desired, adjacent straight portions of the sealing means may be physically attached together so that these straight elements of the sealing means provide an effective tension tie between opposite sides of the air seal assembly.

1 claim:

1. A fluid cushion device of the plenum chamber type capable of supporting superimposed loads of high magnitude comprising:

base means to receive loads,

at least one sealing assembly to confine a fluid cushion,

said sealing assembly comprising an annular hanger projecting from the base means and annular structure projecting from the hanger to close proximity to the support surface under the device to cooperate with the hanger and the support surface as the sole means to retard escape of fluid from the fluid cushion,

said hanger being made of flexible sheet material and being inflatable for vertical resilient deformability,

said annular structure being of less radial dimension than the hanger and being positioned within an annular area defined by the hanger,

the hanger when inflatedhaving an outer annular flexible sheet wall inclining from the base means radially inwardly to the annular structure to act under tension to oppose lateral displacement of the annular structure in one respect relative to the base means, and having an inner annular flexible sheet wall inclining from the base means radially outwardly to the annular structure to oppose lateral displacement of the annular structure in the opposite respect relative to the base means to stabilize the annular structure relative to the base means without need for linking the annular structure directly to the base means,

the maximum cross-sectional dimension of the hanger parallel to said base structure being at the juncture of the hanger and the base structure;

means to inflate said hanger to extend the sealing assembly downward relative to the base means; and

means to supply pressurized fluid to the fluid cushion solely by introducing the pressurized fluid from said base means directly into the cushion.

2. A combination as set forth in claim 1 in which the sealing assembly is on the underside of the base means to form a fluid cushion below the base.

3. A combination as set forth in claim l in which said hanger is constructed of at least one layer of airtight omnidirectionally elastomeric elastic flexible sheet material reinforced by spaced transverse strips of flexible relatively inelastic material.

4. A combination as set forth in claim I wherein said sealing means includes a flexible skirt extending downward from the hanger.

5. A combination as set forth in claim I in which the base means is provided with a plurality of sealing assemblies contiguous to each other and cooperating to define a cavity adjacent the base means, the cavity being enclosed on all sides in a fluid-tight manner by the plurality of sealing assemblies;

said cavity being filled with fluid under pressure from the cooperating sealing assemblies to oppose fluid leakage from the cooperating sealing assemblies into the cavity thereby to reduce peripheral leakage from the plurality of fluid cushions.

6. A combination as set forth in claim 1 in which the annular structure includes sealing means to cooperate with the support surface to retard escape of fluid from the fluid cushion and further includes resilient mounting means attaching the sealing means to the hanger.

7. A combination as set forth in claim 6 in which said mounting means includes zipper means to facilitate removal of the sealing means.

8. A combination as set forth in claim 1 in which the base means is provided with a plurality of sealing assemblies;

at least two of the sealing assemblies being contiguous to each other along a common straight border with opposed fluid pressures of the two corresponding fluid cushions along the common border minimizing leakage of the two corresponding fluid cushoins at the common border.

9. A combination as set forth in claim 8 in which said common straight border is of a length at least approximately equal to one half the cross dimension of one of the two contiguous sealing assemblies.

10. A combination as set forth in claim 1 wherein the base means is provided with a plurality of sealing assemblies;

at least two of the sealing assemblies being adjacent each other with peripheral portions thereof merged together to form a common boundary structure for the corresponding fluid cushions with the common boundary structure under opposite pressures from the two fluid cushions.

11. A combination as set forth in claim 10 which includes means interconnecting the merged portions of said. two hangers.

12. A combination as set forth in claim 10 in which the annular structures of said two sealing assemblies are contiguous to each other along the merged portions of the two sealing assemblies with the radially outward fluid pressure against each of the contiguous portions of the annular stwctures being opposed by the radially outward fluid pressure against the other contiguous portion.

13. A combination as set forth in claim 1 which includes: I

a plurality of sealing assemblies;

at least one passage means to supply fluid for inflating the hangers of the sealing assemblies;

at least one additional passage means to supply fluid for the fluid cushions; and

means to supply pressurized fluid to said passage means.

141. A combination as set forth in claim 13 in which the means to supply fluid under pressure includes an inlet manifold connected to the base means to supply fluid to the respective passage means.

15. A combination as set forth in claim 14 which includes means to vent said additional passage means to the atmosphere to deflate the hangers of the sealing assembly in response to release of the inlet manifold from said base means.

16. A combination as set forth in claim 1 which includes a plurality of sealing assemblies having a corresponding plurality of hangers; in which the means to supply fluid to the fluid cushions includes valve means to cut off the fluid cushions from the supply of fluid; said valve means being responsive to rise in pressure in said hangers to open only after a predetermined pressure rise in the hangers. 17. A combination as set forth in claim 16 which includes a manifold in communication both with said fluid cushions and with said hangers, said valve means being responsive to pressure in the manifold to open in response to pressure rise in the manifold.

18. A combination as set forth in claim 16 in which said valve means comprises a hinged valve member having a flat face on its upstream side to make the valve member responsive to upstream pressure, the valve member having a curved face on its downstream side concentric to its hinge axis to make the valve member substantially nonresponsive to downstream pressure; and

which includes means to bias the valve member to closed position. 

1. A fluid cushion device of the plenum chamber type capable of supporting superimposed loads of high magnitude comprising: base means to receive loads, at least one sealing assembly to confine a fluid cushion, said sealing assembly comprising an annular hanger projecting from the base means and annular structure projecting from the hanger to close proximity to the support surface under the device to cooperate with the hanger and the support surface as the sole means to retard escape of fluid from the fluid cushion, said hanger being made of flexible sheet material and being inflatable for vertical resilient deformability, said annular structure being of less radial dimension than the hanger and being positioned within an annular area defined by the hanger, the hanger when inflated having an outer annular flexible sheet wall inclining from the base means radially inwardly to the annular structure to act under tension to oppose lateral displacement of the annular structure in one respect relative to the base means, and having an inner annular flexible sheet wall inclining from the base means radially outwardly to the annular structure to oppose lateral displacement of the annular structure in the opposite respect relative to the base means to stabilize the annular structure relative to the base means without need for linking the annular structure directly to the base means, the maximum cross-sectional dimension of the hanger parallel to said base structure being at the juncture of the hanger and the base structure; means to inflate said hanger to extend the sealing assembly downward relative to the base means; and means to supply pressurized fluid to the fluid cushion solely by introducing the pressurized fluid from said base means directly into the cushion.
 2. A combination as set forth in claim 1 in which the sealing assembly is on the underside of the base means to form a fluid cushion below the base.
 3. A combination as set forth in claim 1 in which said hanger is constructed of at least one layer of airtight omnidirectionally elastomeric elastic flexible sheet material reinforced by spaced transverse strips of flexible relatively inelastic material.
 4. A combination as set forth in claim 1 wherein said sealing means includes a flexible skirt extending downward from the hanger.
 5. A combination as set forth in claim 1 in which the base means is provided with a plurality of sealing assemblies contiguous to each other and cooperating to define a cavity adjacent the base means, the cavity being enclosed on all sides in a fluid-tight manner by the plurality of sealing assemblies; said cavity being filled with fluid under pressure from the cooperating sealing assemblies to oppose fluid leakage from the cooperating sealing assemblies into the cavity thereby to reduce peripheral leakage from the plurality of fluid cushions.
 6. A combination as set forth in claim 1 in which the annular structure includes sealing means to cooperate with the support surface to retard escape of fluid from the fluid cushion and further includes resilient mounting means attaching the sealing means to the hanger.
 7. A combination as set forth in claim 6 in which said mounting means includes zipper means to facilitate removal of the sealing means.
 8. A combination as set forth in claim 1 in which the base means is provided with a plurality of sealing assemblies; at least two of the sealing assemblies being contiguous to each other along a common straight border with opposed fluid pressures of the two corresponding fluid cushions along the common border minimizing leakage of the two corresponding fluid cushoins at the common border.
 9. A combination as set forth in claim 8 in which said common straight border is of a length at least approximately equal to one half the cross dimension of one of the two contiguous sealing assemblies.
 10. A combination as set forth in claim 1 wherein the base means is provided with a plurality of sealing assemblies; at least two of the sealing assemblies being adjacent each other with peripheral portions thereof merged together to form a common boundary structure for the corresponding fluid cushions with the common boundary structure under opposite pressures from the two fluid cushions.
 11. A combination as set forth in claim 10 which includes means interconnecting the merged portions of said two hangers.
 12. A combination as set forth in claim 10 in which the annular structures of said two sealing assemblies are contiguous to each other along the merged portions of the two sealing assemblies with the radially outward fluid pressure against each of the contiguous portions of the annular structures being opposed by the radially outward fluid pressure against the other contiguous portion.
 13. A combination as set forth in claim 1 which includes: a plurality of sealing assemblies; at least one passage means to supply fluid for inflating the hangers of the sealing assemblies; at least one additional passage means to supply fluid for the fluid cushions; and means to supply pressurized fluid to said passage means.
 14. A combination as set forth in claim 13 in which the means to supply fluid under pressure includes an inlet manifold connected to the base means to supply fluid to the respective passage means.
 15. A combination as set forth in claim 14 which includes means to vent said additional passage means to the atmosphere to deflate the hangers of the sealing assembly in response to release of the inlet manifold from said base means.
 16. A combination as set forth in claim 1 which includes a plurality of sealing assemblies having a corresponding plurality of hangers; in which the means to supply fluid to the fluid cushions includes valve means to cut off the fluid cushions from the supply of fluid; said valve means being responsive to rise in pressure in said hangers to open only after a predetermined pressure rise in the hangErs.
 17. A combination as set forth in claim 16 which includes a manifold in communication both with said fluid cushions and with said hangers, said valve means being responsive to pressure in the manifold to open in response to pressure rise in the manifold.
 18. A combination as set forth in claim 16 in which said valve means comprises a hinged valve member having a flat face on its upstream side to make the valve member responsive to upstream pressure, the valve member having a curved face on its downstream side concentric to its hinge axis to make the valve member substantially nonresponsive to downstream pressure; and which includes means to bias the valve member to closed position. 